CN101042548A - Image forming apparatus and developer cartridge - Google Patents

Abstract

The frame body (36) of the developing cartridge (24) is provided with an elastic member (91) for applying force in the direction of pushing the developing roller (39) to the photosensitive drum (31). When the developer cartridge (24) is replaced with a new product, the elastic member (91) also becomes a new product, so it will not continue to be used in a state where the applied force of the elastic member (91) is reduced, and the development roller (39) can be continuously maintained. Good pushing state of the photosensitive drum (31). The amount of toner supplied from the developing roller (39) to the photosensitive drum (31) is stable, and no defective development occurs, and high-quality images can be continuously formed.

Description

Image forming device and developing cartridge

Field of Invention

The present invention relates to an image forming apparatus such as a laser printer, and a developing cartridge equipped in the image forming apparatus.

Background technique

The laser printer disclosed in Japanese Patent Application Laid-Open No. 2003-15378 has an image carrier cartridge that supports image carriers corresponding to a plurality of colors. The image carrier cartridge is detachably set on the laser printer. The developing cartridges corresponding to the respective colors are detachable to the image carrier cartridge.

The developing cartridge includes a developing roller for supplying toner to the image carrier. In order to transfer the toner from the developing roller to the image carrier well, the developing roller has to contact the image carrier with an appropriate urging force. In the laser printer, there is an elastic member such as a spring, the elastic member acts on the developing cartridge, and the developing roller is pushed against the image carrier.

However, as the elastic member deteriorates, the elasticity of the elastic member gradually decreases. If the elasticity of the elastic member is reduced, the pressing force of the developing roller on the image carrier will be reduced, so that the supply amount of toner supplied to the image carrier may be insufficient.

Contents of Invention

An object of the present invention is to continuously maintain a good pressing state of the developer carrier against the image carrier.

Description of drawings

Fig. 1 is a sectional view of a color laser printer.

FIG. 2 is a perspective view of the processing unit shown in FIG. 1 .

Fig. 3 is a perspective view of the developing cartridge shown in Fig. 1 .

Fig. 4 is a rear view of the developing cartridge shown in Fig. 3 .

Fig. 5 is a front view of the developing cartridge shown in Fig. 3 .

Fig. 6 is a right side view of the developing cartridge shown in Fig. 3 .

Fig. 7 is a left side view of the developing cartridge shown in Fig. 3 .

Fig. 8 is a perspective view of a drum unit, left and right rails, and a separation pressing mechanism.

Fig. 9 is a perspective view of the separation pressing mechanism shown in Fig. 8 .

10A to 10E are perspective views of the linear motion cam member and the intermediate member shown in FIG. 9 , showing respective states in the middle of separation and pushing operations of each separation pressing mechanism.

Fig. 11 is a right side view of the linear cam member and the intermediate member in the state shown in Fig. 10A.

Fig. 12 is a right side view of the linear cam member and the intermediate member in the state of Fig. 10C.

Fig. 13 is a right side view of the linear cam member and the intermediate member in the state of Fig. 10E.

Detailed ways

1. The overall composition of the color laser printer

As shown in FIG. 1 , in a color laser printer, a plurality of auxiliary units 25 are arranged horizontally in a box-shaped casing 2 . Inside the casing 2 , there are a paper feeding section 4 for feeding paper 3 , an image forming section 5 for forming an image on paper 3 , and a paper discharge section 6 for discharging paper 3 .

(1) Housing

On the side wall of the casing 2, a front cover 7 for opening or closing the inside of the casing 2 is provided. The front cover 7 is rotatable around its lower end. The processing unit 18 can be attached to and detached from the casing 2 by sliding the processing unit 18 in the front-rear direction with the front cover 7 opened.

In the following description, the side on which the front cover 7 is provided, that is, the left side in FIG. 1 is referred to as the front side, and the right side in FIG. 1 is referred to as the rear side. The left and right reference is made when the color laser printer 1 is viewed from the front side. In addition, as long as the drum unit 23 and the developing cartridge 24 are not mentioned in particular, they are mounted on the housing 2, front, rear, left, right, up, down.

(2) Feeding section

The paper feeder 4 is provided at the bottom inside the housing 2 . Paper feed unit 4 has tray 8 for storing paper 3 , separation roller 9 and separation table 10 provided above the front end of tray 8 , and paper feed roller 11 provided behind separation roller 9 .

Inside the paper feed tray 8, a paper pressing plate 12 is provided. Paper sheets 3 are stacked on the paper pressing plate 12 . The uppermost paper 3 is pushed by the paper feed roller 11 .

If the paper feeding roller 11 rotates, the uppermost paper 3 is sent into between the separation roller 9 and the separation platform 10 . The paper 3 is sandwiched between the separation roller 9 and the separation table 10 and conveyed to the conveyance path 13 .

In the middle of the conveyance path, a paper dust removal roller 14 and a pinch roller 15 provided above the front side of the separation roller 9 , and a pair of registration rollers 16 are provided.

Paper 3 conveyed on conveyance path 13 passes between paper dust removal roller 14 and pinch roller 15 . While passing, paper dust generated on the paper 3 is removed. In addition, the paper 3 is conveyed by the registration roller 16 to the conveyance belt 48 .

(3) Image forming department

The image forming unit 5 has an exposure device 17 , a processing unit 18 , a transfer mechanism 19 , and a fixing device 20 .

(3-1) Exposure device

The exposure device 17 is disposed on the upper portion of the housing 2 . The exposure device 17 has a support plate 21 and a cover 22 for accommodating optical elements such as a laser light emitting unit and a polygon mirror.

In the exposure device 17 , laser light beams corresponding to image data of respective colors of black, yellow, magenta, and cyan are emitted from a laser light emitting unit. The laser beam is scanned by a polygon mirror and irradiated onto the surface of the photosensitive drum 31 .

(3-2) Processing unit

The processing unit 18 has a drum unit 23 as an example of an image carrier unit, and four developing cartridges 24 corresponding to the respective colors of black, yellow, magenta, and cyan.

(3-2-1) drum unit

As shown in FIGS. 1 and 2 , the drum unit 23 includes a pair of side plates 26 . Between a pair of side plates 26, four auxiliary units 25 corresponding to respective colors are interposed. In FIG. 2 , only the side plate 26 on the right side is illustrated. A front beam 27 is fixed between front end portions of the pair of side plates 26 . A front handle portion 28 is provided on the front beam 27 . A rear beam 29 is fixed between rear end portions of the pair of side plates 26 . The rear handle portion 30 is provided on the rear beam 29 . The distance between the pair of side plates 26 is prescribed by the front beam 27 and the rear beam 29 . Four auxiliary units 25 are housed in a space formed by the pair of side plates 26 , the front beam 27 , and the rear beam 29 .

The four auxiliary units 25 are arranged side by side at intervals along the front-rear direction. As shown in FIG. 1 , the black auxiliary unit 25K, the yellow auxiliary unit 25Y, the magenta auxiliary unit 25M, and the cyan auxiliary unit 25C are sequentially arranged from the front side to the rear side.

Each auxiliary unit 25 holds a photosensitive drum 31 , a charger 32 , and a cleaning brush 33 .

The photosensitive drum 31 has a drum shaft 34 supported by the pair of side plates 26 and a drum body 35 rotatably provided on the drum shaft 34 .

The charger 32 is arranged at a distance from the photosensitive drum 31 . The charging body 32 generates corona discharge to uniformly charge the surface of the photosensitive drum 31 . The cleaning brush 33 is in contact with the photosensitive drum 31 .

(3-2-2) Developing cartridge

The developing cartridges 24 include a developing cartridge 24K for black, a developing cartridge 24Y for yellow, a developing cartridge 24M for magenta, and a developing cartridge 24C for cyan. As shown in FIG. 1, the developing cartridge 24K for black is detachably attached to the auxiliary unit 25K for black. The yellow developing cartridge 24Y is detachably attached to the yellow auxiliary unit 25Y. The developing cartridge 24M for magenta is detachably attached to the auxiliary unit 25M for magenta. The developing cartridge 24C for cyan is detachably attached to the auxiliary unit 25C for cyan.

Each developer cartridge 24 is attached to the auxiliary unit 25 corresponding to the developer cartridge 24 from above the drum unit 23 .

Each developer cartridge 24 is equipped with the frame body 36 which has an opening in the lower end, respectively. A stirring device 37 , a supply roller 38 , a developing roller 39 , and a layer thickness regulating sheet 40 are provided in the frame body 36 .

Inside the housing 36, toner is accommodated. Black toner is accommodated inside the housing 36 of the black developing cartridge 24K. Yellow toner is housed inside the housing 36 of the developing cartridge 24Y for yellow. Magenta toner is housed inside the casing 36 of the developing cartridge 24M for magenta. A cyan toner is stored in the cyan developing cartridge 24C. The toners of each color are positively charged non-magnetic one-component polymerized toners, and black, yellow, magenta, and cyan colorants are blended corresponding to each color.

Stirring device 37 is provided in the upper part of frame body 36 . Stirring device 37 is rotated by a driving force from a motor provided in housing 2 to stir the toner in housing 36 .

The supply roller 38 is provided below the stirring device 37 . The supply roller 38 includes a metal supply roller shaft 41 rotatably supported by the frame body 36 , and a sponge roller 42 made of a conductive sponge covering the supply roller shaft 41 . The supply roller 38 is rotated by a driving force from a motor provided in the casing 2 .

The developing roller 39 includes a metallic developing roller shaft 43 rotatably supported by the frame body 36 , and a rubber roller 44 made of conductive rubber covering the periphery of the developing roller shaft 43 . The developing roller 39 is disposed obliquely below the rear side with respect to the supply roller 38 , and the rubber roller 44 and the sponge roller 42 are in contact with each other. The developing roller 39 is disposed at a position exposed from an opening at the lower end of the housing 36 . When the developing cartridge 24 is mounted on the auxiliary unit 25, the developing roller 39 contacts the photosensitive drum 31 obliquely forward. The developing roller 39 is rotated by a driving force from a motor provided in the casing 2 .

The base end portion of the layer thickness regulating piece 40 is supported by the frame body 36 , and the movable end portion extends above the developing roller 39 . A pressing portion 45 made of insulating silicone rubber is provided at the movable end portion of the layer thickness regulating piece 40 . The pressing portion 45 abuts against the rubber roller 44 of the developing roller 39 from above.

(3-2-3) Developing action

In each developing cartridge 24 , the toner contained in the housing 36 is supplied to the supply roller 38 by its own weight while being stirred by the stirring device 37 . The toner supplied to the supply roller 38 is supplied to the developing roller 39 by the rotation of the supply roller 38 . The toner supplied to the developing roller 39 enters between the pressing portion 45 of the layer thickness regulating sheet 40 and the developing roller 39 as the developing roller 39 rotates, forms a thin layer with a certain thickness, and is carried on the surface of the developing roller 39 .

On the other hand, in the auxiliary unit 25 corresponding to each developing cartridge 24 , the surface of the photosensitive drum 31 is uniformly charged by the charger 32 . When the laser beam from the exposure device 17 is irradiated onto the surface of the photosensitive drum 31 , an electrostatic latent image is formed on the surface of the photosensitive drum 31 .

When the photosensitive drum 31 further rotates, the toner carried on the surface of the developing roller 39 is supplied onto the electrostatic latent image formed on the surface of the photosensitive drum 31 . In this way, the electrostatic latent image is visualized, and toner images corresponding to various colors are carried on the surface of the photosensitive drum 31 .

(3-3) Transfer mechanism

As shown in FIG. 1 , the transfer mechanism 19 is arranged above the paper feeding unit 4 and below the processing unit 18 in the casing 2 . The transfer mechanism 19 has a driving roller 46 , a driven roller 47 , a conveyance belt 48 , a transfer roller 49 , and a cleaning mechanism 50 .

The drive roller 46 is arranged at intervals in the front-rear direction with respect to the driven roller 47 . The drive roller 46 is arranged further in front of the black auxiliary unit 25K, and the driven roller 47 is arranged further rearward of the yellow auxiliary unit 25Y.

The conveyor belt 48 is an endless belt formed of a resin sheet such as polycarbonate or polyimide in which conductive particles (for example, carbon particles) are dispersed. The conveyor belt 48 is stretched between the driving roller 46 and the driven roller 47 .

The driving roller 46 is rotated by a driving force from a motor (not shown) provided in the casing 2 . Then, the conveyance belt 48 rotates around between the driving roller 46 and the driven roller 47 .

The transfer roller 49 is arranged inside the track of the conveyance belt 48 . The transfer rollers 49 are provided corresponding to the photosensitive drums 31 for the respective colors. The conveyance belt 48 is sandwiched between the transfer roller 49 and the photosensitive drum 31 . The transfer roller 49 is driven to rotate in the same direction as the moving direction of the conveyance belt 48 .

The cleaning mechanism 50 is arranged below the conveyor belt 48 and has a primary cleaning roller 51 , a secondary cleaning roller 52 , a scraper blade 53 , and a toner storage portion 54 .

The primary cleaning roller 51 is arrange|positioned so that it may contact the outer peripheral surface of the conveyance belt 48 from below.

The secondary cleaning roller 52 is arranged so as to be in contact with the primary cleaning roller 51 from below. The scraper blade 53 is provided so as to contact the secondary cleaning roller 52 from below.

The toner storage unit 54 is provided below the primary cleaning roller 51 and the secondary cleaning roller 52 , and stores toner dropped from the secondary cleaning roller 52 .

The sheet 3 that has passed the registration rollers 16 is conveyed from the front side to the rear side by the conveyance belt 48 . While the paper 3 is conveyed on the surface of the conveyance belt 48 , the toner images of the respective colors carried on the photosensitive drums 31 are sequentially transferred onto the paper 3 . In this way, a color image is formed on the paper 3 .

First, the black toner image carried on the surface of the photosensitive drum 31 of the auxiliary unit 25K for black is transferred onto the paper 3 . Next, the yellow toner image carried on the surface of the photosensitive drum 31 of the yellow auxiliary unit 25Y is superimposedly transferred to the position where the black toner image was transferred. Next, the magenta toner image carried on the surface of the photosensitive drum 31 of the auxiliary unit 25M for magenta and the cyan toner image carried on the surface of the photosensitive drum 31 of the auxiliary unit 25C for cyan are separated by the same operation. Transfer to paper 3 in sequence overlapping. In this way, a color image in which the toner images of the respective colors are superimposed is formed on the sheet 3 .

The toner remaining on the photosensitive drum 31 after transfer is recovered by the developing roller 39 . The paper dust of the paper 3 adhering to the photosensitive drum 31 after transfer is recovered by the cleaning brush 33 .

On the other hand, the toner adhering to the surface of the conveyance belt 48 is first transferred from the surface of the conveyance belt 48 to the primary cleaning roller 51 , and then transferred from the primary cleaning roller 51 to the secondary cleaning roller 52 . The toner transferred to the secondary cleaning roller 52 is scraped off by the scraper blade 53 , falls from the secondary cleaning roller 52 , and is stored in the toner storage portion 54 .

(3-4) Fixing device

The fixing device 20 is disposed on the housing 2 further behind the cyan auxiliary unit 25C. The fixing device 20 has a heating roller 55 and a pressure roller 56 .

The heat roller 55 has a release layer formed on the surface of the metal tube. A halogen lamp is provided inside the heat roller 55 . The surface of the heating roller 55 is heated by the heat generated by the halogen lamp.

The pressure roller 56 is disposed below the heating roller 55 and presses the heating roller 55 from below.

The color image transferred on the paper 3 is conveyed to the fixing device 20 . The color image is fixed to the paper 3 while the paper 3 passes between the heat roller 55 and the pressure roller 56 . The paper 3 on which the color image is fixed is conveyed to the paper discharge unit 6 by the heat roller 55 and the pressure roller 56 .

(4) Paper discharge department

The paper 3 sent from the fixing device 20 is conveyed to the conveyance path 57 . The upstream end of the transport path 57 is adjacent to the fixing device 20 , and the downstream end is adjacent to the paper discharge tray 58 formed on the upper surface of the housing 2 .

In the middle of the conveyance path 57, the conveyance roller 59 and the pinch roller 60 are provided facing each other. A pair of discharge rollers 61 are provided at the downstream end of the transport path 57 .

Paper 3 is conveyed to conveyance path 57 by conveyance roller 59 and pinch roller 60 , and is discharged to paper discharge tray 58 by paper discharge roller 61 .

2. The frame of the developer box

The housing 36 of the developing cartridge 24 has a left side wall 71L and a right side wall 71R opposite to the left side wall 71L. The upper wall 72 is bridged between the upper end side of the side wall 71L and the upper end side of the side wall 71R. The front wall 73 is bridged between the front end of the side wall 71L and the front end of the side wall 71R. A rear wall 74 is bridged between the rear end side of the side wall 71L and the rear end side of the side wall 71R. The side wall 71L, the side wall 71R, the upper wall 72 , the front wall 73 , and the rear wall 74 are integrally formed of resin. The lower end of the frame body 36 is opened, and the developing roller 39 is exposed from the opened portion.

Windows 75 are respectively provided on the side wall 71L and the side wall 71R. The window 75 is oppositely formed, and light can pass through the window 75 . By detecting the passing light, the amount of remaining toner in the housing 36 can be detected.

As shown in FIG. 7 , a gear mechanism portion covered by a gear cover 76 is provided on the left side wall 71L. The gear mechanism unit has a coupling 77 exposed from the gear cover 76 and a gear train for transmitting the driving force input to the coupling 77 .

At the lower end portion of the gear cover 76, a cylindrical gear arrangement portion 78 is formed so as to protrude outward. The coupling 77 is arranged in the gear arrangement part 78 and exposed from the front end surface of the gear arrangement part 78 .

A coupling shaft provided in the casing 2 is coupled to the coupling 77 . The driving force of the motor provided in the housing 2 is input to the coupling 77 from the coupling shaft.

The gear train has an agitator gear fixed on the rotation shaft of the agitator 37, a supply roller gear fixed on the supply roller shaft 41 of the supply roller 38, a developing roller gear fixed on the developing roller shaft 43 of the developing roller 39, and the like. The driving force of the input coupling 77 is transmitted to the stirring device 37, the supply roller 38, and the developing roller 39 through a gear train.

As shown in FIGS. 3 and 6 , a toner filling port is formed obliquely above the window 75 on the right side wall 71R. A cap 79 is arranged at the filling port, and the cap 79 closes the filling port.

On the lower end portion of the right side wall 71R, a bearing 80 that rotatably supports the end portion of the developing roller shaft 43 is provided. End portions of the developing roller shaft 43 protrude outward from the gear cover 76 and the bearing member 80 , respectively, and the protruding portions are covered with flanges 81 .

As shown in FIGS. 3-7 , on the upper ends of the side wall 71L and the side wall 71R, a substantially cylindrical first protrusion 82 protruding outward in the left-right direction from the connection portion with the upper end portion of the rear wall 74 is formed. .

In addition, elastic members 91 are respectively provided at the upper end portions of the side wall 71L and the side wall 71R, in the vicinity of the first protrusion 82 , at connecting portions with the front wall 73 .

The elastic member 91 is processed by a leaf spring. One end of the elastic member 91 is a fixing portion 92 . The fixing portion 92 is fixed on the outer surface of the side wall 71 by screws 93 . The elastic member 91 extends upward from the fixing portion 92 , and extends curved outward in the left-right direction at a position above the upper wall 72 . The other end of the elastic member 91 is a second protrusion 94 . The second protrusion 94 protrudes further outward in the left-right direction of the side wall 71 , and the tip portion is curved in a substantially semicircular shape when viewed from the side.

3. Separation and pushing mechanism

Inside the casing 2, a pair of frames that are arranged to face each other in the left-right direction with the drum unit 23 in between are provided. A rail 302 and a separation pushing mechanism 303 are provided on the inner surface of each frame. The rail 302 guides attachment and detachment of the drum unit 23 . The separating pushing mechanism 303 acts on the developing cartridge 24 to push the developing roller 39 toward the photosensitive drum 31 and also separate the developing roller 39 from the photosensitive drum 31 .

The rails 302 are disposed opposite to each other with the drum unit 23 in between. The rail 302 extends in the front-rear direction.

The separation pushing mechanism 303 is arranged above the track 302 . The separation pushing mechanism 303 has, as shown in FIGS. 8 and 9 , a pair of straight-acting cam parts 310, an intermediate part 311 provided corresponding to each straight-acting cam part 310, and each straight-acting cam part 310 can be kept linearly movable in the front-rear direction. The cam bracket 312 and the synchronous movement mechanism 313 that make a pair of linear motion cam parts 310 linearly move synchronously.

In FIG. 9 , illustration of the cam holder 312 is omitted.

As shown in FIGS. 9-13 , the linear motion cam member 310 has a thin-plate cam body plate 314 extending in the front-rear direction and four operating members 315 provided on the inner side of the cam body plate 314 in the left-right direction.

In the cam body plate 314, four substantially rectangular holes 316 are formed at equal intervals in the front-rear direction and are elongated in the front-rear direction.

The four operation members 315 are arranged on the respective front sides of the four rectangular holes 316 . Each operation member 315 is integrally composed of a pressing action part 317 , a contact and separation action part 318 , and a connection part 319 . The pressing action portion 317 is crank-shaped in side view, extends along the upper edge of the cam body plate 314 , and presses the second protrusion 94 of the developing cartridge 24 downward. The contact and separation action portion 318 extends along the lower end side of the cam body plate 314 to rotate the intermediate member 311 . The connection portion 319 connects the rear end portion of the pressing action portion 317 and the front end portion of the contact separation action portion 318 .

As shown in FIGS. 11 to 13 , a protrusion 320 protruding upward is formed at the rear end portion of the contact separation action portion 318 .

The frontmost operation member 315 is different in shape from the remaining three operation members 315 (hereinafter referred to as "three rear operation members 315"). That is, the pressing portion 317 of the frontmost operation member 315 is longer in the front-rear direction than the pressing portions 317 of the three rear operation members 315 . In addition, the contact-and-separation action part 318 of the frontmost operation member 315 is shorter in the front-rear direction than the contact-and-separation action parts 318 of the three rear-side operation members 315 . This difference in shape is necessary to realize the following states.

1. Push the developing rollers 39 of all the developing cartridges 24 to the photosensitive drum 31,

2. Only the state where the developing roller 39 of the black developing cartridge 24K is pressed against the photosensitive drum 31,

3. A state where the developing rollers 39 of all the developing cartridges 24 are separated from the photosensitive drums 31

The four intermediate members 311 are arranged on the respective rear sides of the four operation members 315 . The four intermediate members 311 are respectively opposed to the four rectangular holes 316 in the left-right direction. As shown in FIGS. 11 to 13 , each intermediate member 311 has a substantially L-shape when viewed from the side, and is formed in a thick block shape in the left-right direction.

A support shaft 321 penetrates through one end of the intermediate member 311 in the left-right direction. The intermediate member 311 is supported on the support shaft 321 and can rotate around the support shaft 321 . In a state where each intermediate member 311 is not in contact with the contact/separation action portion 318 , the lower end portion of the intermediate member 311 is spaced apart from the protrusion 320 of the contact/separation action portion 318 in the front-rear direction as shown in FIG. 11 .

The support shafts 321 are arranged at equal intervals in the front-rear direction as shown in FIG. 10 . This interval is equal to the interval between the first protrusions 82 provided on the respective developing cartridges 24 in a state where four developing cartridges 24 are mounted on the drum unit 23 . The supporting shaft 321 is inserted through the corresponding rectangular hole 316 . The outer end of the support shaft 321 extends from the cam body plate 314 to the outside in the left-right direction, and the inner end is fixed on the cam bracket 312, and the support shaft 321 cannot rotate.

As shown in FIG. 8 , the cam holder 312 integrally has a thin plate-shaped holder fixing portion 322 extending in the front-rear direction and a cam receiving portion 323 connected to the lower end of the holder fixing portion 322 .

The bracket fixing part 322 is fixed on the inner surface of the frame in the casing 2 by screws 324 .

The cam accommodating portion 323 extends inwardly in the left-right direction from the entire length of the lower end side of the bracket fixing portion 322 , bends downward, and then bends outward in the left-right direction to form a substantially U-shaped cross section. On the upper surface of the cam housing part 323, four second housing parts 325 and first housing parts 326 are alternately formed.

The second accommodating portion 325 is a notch formed continuously from the upper surface to the inner surface of the cam accommodating portion 323 , and can accommodate the second protrusion 94 of the developing cartridge 24 .

The first accommodating portion 326 is a notch formed continuously from the upper surface to the inner surface of the cam accommodating portion 323 , and can accommodate the first protrusion 82 on the developing cartridge 24 .

Therefore, when each developer cartridge 24 is mounted on the drum unit 23 , the intervals between the four second receiving portions 325 formed on the cam receiving portion 323 are the same as the intervals between the second protrusions 94 in the front-rear direction. The intervals between the four first housing portions 326 are equal to the intervals between the first protrusions 82 in the front-rear direction.

The first storage part 326 is disposed behind the second storage part 325 . In a state where the first protrusion 82 is accommodated in the first accommodation portion 326 , the first protrusion 82 faces the intermediate member 311 from above.

The synchronous movement mechanism 313 transmits the driving force from the left linear motion cam member 310 to the right linear motion cam member 310 along with the linear movement of the left linear motion cam member 310 .

The synchronous movement mechanism 313 is composed of a left rack 327 , a left pinion 328 , a right rack 329 , a right pinion 330 , and a connecting shaft 331 as shown in FIG. 9 . The left rack 32732 is formed on the upper surface of the rear end portion of the left linear motion cam member 310 . The left pinion 328 meshes with the left rack 327 . The right rack 329 is formed on the upper surface of the rear end portion of the right linear motion cam member 310 . The right pinion 330 meshes with the right rack 329 . A left pinion 328 and a right pinion 330 are attached to the connecting shaft 331 .

An input rack 332 to which a driving force from a motor is input is provided on the left linear motion cam member 310 .

4. Separation push action

The operation of the separation pressing mechanism 303 will be described with reference to FIGS. 10-13 .

As shown in FIG. 10A and FIG. 11 , when the linear motion cam member 310 has moved to the frontmost position, the contact and separation action portion 318 and the intermediate member 311 face each other with a gap in the front-rear direction. The distance between the frontmost contact and separation action portion 318 and the intermediate member 311 is larger than the intervals between the rear three contact and separation action portions 318 and the intermediate member 311 .

In this state, as shown in FIG. 11 , the pressing action portion 317 comes into contact with the second protrusion 94 from above, and presses the second protrusion 94 downward. The second protrusion 94 is elastically deformed by being pushed down. A restoring force acts on the second protrusion 94 , and the restoring force is transmitted to the side wall 71 through the fixing portion 92 . Thus, the frame body 36 is urged downward, and the developing roller 39 is pressed against the photosensitive drum 31 . In this state, since all four developing cartridges 24 are urged downward, full-color printing can be performed.

When a driving force is input to the input rack 332 from this state, the left linear motion cam member 310 moves rearward. As the left linear motion cam member 310 moves, the left pinion gear 328 rotates. The rotation of the left pinion 328 is transmitted to the right pinion 330 through the connecting shaft 331 . Since the right pinion 330 rotates in the same direction as that of the left pinion 328, the right linear motion cam member 310 moves rearward.

When the linear motion cam member 310 moves backward, the engagement between the three rear pressing portions 317 and the second protrusion 94 is released. In this way, the pressing of the second protrusion 94 by the pressing action portion 317 is released.

As shown in FIG. 10B , the three contact and separation action portions 318 on the rear side contact the lower end of the intermediate member 311 to press the lower end of the intermediate member 311 backward. In this way, the intermediate member 311 turns so as to rise upward with the support shaft 321 as a fulcrum. In the middle of the rotation of the intermediate member 311 , the intermediate member 311 comes into contact with the first protrusion 82 from below. Since the intermediate member 311 applies an upward force to the first protrusion 82 , the developing cartridge 24Y for yellow, the developing cartridge 24M for magenta, and the developing cartridge 24C for cyan are lifted upward.

If the linear motion cam member 310 is further moved backward, as shown in FIG. 10C and FIG. 12, one end of the intermediate member 311 abuts against the upper surfaces of the three contacting and separating action portions 318 on the rear side, and the yellow developing cartridge 24Y, product The developing rollers 39 of the developing cartridge 24M for red and the developing cartridge 24C for cyan are separated from the respective photosensitive drums 31 . At this time, the second protrusion 94 of the black developing cartridge 24K is pressed by the pressing action portion 317 . That is, only the developing roller 39 of the black developing cartridge 24K is pressed against the photosensitive drum 31 . Black and white printing is possible in this state.

If the straight-acting cam member 310 moves further backward, the engagement of the forwardmost pushing action portion 317 with the second protrusion 94 of the black developing cartridge 24K is released, so the pushing force of the pushing action portion 317 on the second protrusion 94 is released. pressure is released. As shown in FIG. 10D , the frontmost contact and separation action portion 318 comes into contact with the lower end of the intermediate member 311 and presses the lower end of the intermediate member 311 backward. The intermediate member 311 turns so as to rise upward with the support shaft 321 as a fulcrum. During the rotation of the intermediate member 311, the intermediate member 311 abuts on the first projection 82 of the developing cartridge 24K for black from below. Since the intermediate member 311 applies an upward force to the first protrusion 82, the black developing cartridge 24K is lifted upward.

If the linear motion cam member 310 moves further backward, as shown in FIG. 10E and FIG. 13 , one end portion of the intermediate member 311 abuts against the upper surface of the frontmost contacting and separating action portion 318, and the developing roller 39 of the developing cartridge 24K for black Separated from the photosensitive drum 31 . In this way, the developing rollers 39 of all the developing cartridges 24 are separated from the photosensitive drums 31 .

If the linear motion cam member 310 is moved forward from the state shown in FIG. 10E, it can return to each state shown in FIGS. 10A-10D. The projection part 320 of the contact separation action part 318 is engaged with the intermediate member 311, and the intermediate member 311 is rotated downward. The intermediate part 311 is separated from the first protrusion 82 .

5. Effect

Since the developer cartridge 24 has the elastic member 91 as described above, when the developer cartridge 24 is replaced with a new product, the elastic member 91 is also a new product. As a result, the biasing force of the elastic member 91 is always good, and the pressing state of the developing roller 39 against the photosensitive drum 31 can be continuously maintained well. Therefore, the amount of toner supplied from the developing roller 39 to the photosensitive drum 31 can always be stabilized, and high-quality images can be continuously formed without occurrence of defective development.

Also, since the elastic member 91 is fixed to the side wall 71L by the screw 93, when the specifications of the toner and the development roller 39 are changed, an elastic member 91 having an appropriate elastic force corresponding to the specification can be used. Thereby, the pressing force of the developing roller 39 on the photosensitive drum 31 can be maintained optimally, and toner can be satisfactorily supplied from the developing roller 39 to the photosensitive drum 31 . Therefore, the amount of toner supplied from the developing roller 39 to the photosensitive drum 31 can always be stabilized, and high-quality images can be continuously formed without occurrence of defective development.

Also, the fixing portion 92 of the elastic member 91 is fixed to the side wall 71 of the developer cartridge 24 , and the second protrusion 94 is provided to protrude outward in the left-right direction from the side wall 71 . Therefore, a place for disposing the separation pressing mechanism 303 for inputting a pressing force to the second protrusion 94 can be easily ensured in the housing 2 . Also, the pressing force from the separation pressing mechanism 303 acts on the second protrusion 94 reliably.

Since the elastic member 91 is formed of a metal leaf spring, the second protrusion 94 is elastically deformable. The restoring force generated by this elastic deformation acts as a force pressing the developing roller 39 against the photosensitive drum 31 . Thereby, a force for pressing the developing roller 39 to the photosensitive drum 31 can be obtained with a simple structure.

Since the elastic members 91 are respectively provided on the side walls 71L, 71R in the left and right direction of the housing 36 of the developing cartridge 24 , the developing roller 39 can press the photosensitive drum 31 in a balanced manner. Therefore, the supply amount of toner from the developing roller 39 can be made uniform in the axial direction of the photosensitive drum 31 . As a result, the electrostatic latent image can be visualized favorably.

Claims (9)

1. An image forming apparatus, characterized in that, has a shell (2); an image carrier unit (23) detachable with respect to the housing; and a developing cartridge (24) detachable relative to the image carrier unit, The image carrier unit (23) has an image carrier (31), The developing cartridge (24) has a frame (36) for accommodating developer; and a developer carrier (39) supported on the frame and carrying developer on the surface, The frame body (36) has a pair of side walls (71L, 71R) opposing in the first direction; and A force applying mechanism (91) fixed on the pair of side walls along the first direction. 2. The image forming apparatus according to claim 1, wherein the urging mechanism comprises a fixing portion (92) fixed to the side wall and a protruding portion (94) protruding outward from the side wall along the first direction. 3. The image forming apparatus according to claim 2, wherein the protrusion (94) has elasticity. 4. The image forming apparatus according to claim 3, wherein the urging mechanism (91) is a leaf spring. 5. The image forming apparatus according to claim 2 or 3, comprising a pair of pressing mechanisms for inputting a pressing force to the protrusion. 6. A developer cartridge, characterized in that it has a frame (36) for accommodating developer; and a developer carrier (39) supported on the frame and carrying developer on the surface, The frame body (36) has a pair of side walls (71L, 71R) opposing in the first direction; and A force applying mechanism (91) fixed on the pair of side walls along the first direction. 7. The developing cartridge according to claim 6, characterized in that, the force applying mechanism comprises a fixing portion (92) fixed on the side wall and a protruding portion (94) protruding outward from the side wall along the first direction. 8. The developing cartridge according to claim 7, characterized in that the protrusion (94) is elastic. 9. The developing cartridge according to claim 8, characterized in that the biasing mechanism (91) is a leaf spring.

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